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biology 2 Flashcards

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MCAT flashcards
1
Q

What are the functions of the kidneys?

A

excrete waste, maintain pH, osmolarity and blood pressure

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2
Q

What is the glomerulus?

A

fenestrated capillary bed that strains the blood- allowing fluids, ions and molecules the approximate size of glucose or smaller to pass through

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3
Q

What is the bowman’s capsule?

A

spherical enclosure around glomerulus

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4
Q

What is reabsorbed and excreted in the Proximal convoluted tubule of the nephron?

A

Along the PCT sodium is reabsorbed via active transport, and glucose is reabsorbed via secondary active transport through a symporter identical to the one used to absorb glucose from the small intestine. Water follows the solutes via facilitated diffusion

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5
Q

What is permeable in the descending loop of Henle?

A

impermeable to salts, but very permeable to water. Water therefore flows out of the filtrate and into the medulla, concentrating the urine

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6
Q

What is the function of the ascending loop of Henle?

A

carries the filtrate out of the medulla and back into the cortex. This portion of the loop is impermeable to water and actively transports ions out of the filtrate and into the medulla. This continuous “dumping” of salts into the medulla accounts for its hypertonicity. At the top of the ascending loop the filtrate is actually less concentrated due to the removal of these ions.

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7
Q

What happens in the distal convoluted tubule?

A

The distal convoluted tubule regulates calcium, sodium and hydrogen concentrations

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8
Q

What does the hormone aldosterone do?

A

stimulates increased sodium reabsorption at the DCT and the collecting duct

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9
Q

What does the collecting duct do?

A

The collecting duct carries the filtrate through the medulla toward the renal pelvis. The collecting duct becomes very permeable to water in the presence of ADH from the posterior pituitary. If ADH is present the filtrate will be further concentrated as water flows out into the very salty medulla

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10
Q

What is the function of the juxtaglomerular apparatus?

A

formed by glomerular afferent arteriole and distal convoluted tubule. Main function is regulating blood pressure and filtrate of glomerulus

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11
Q

Explain the renin-angiotensin-aldosterone system

A 
When BP falls, kidney releases renin into bloodstream 
renin splits angiotensin from liver into angiotensin 1
ACE splits angiotensin 1 into angiotensin 2
angiotensin 2 (hormone) causes vasoconstriction of arterioles 
angiotensin 2 stimulates release of aldosterone and vasopressin
Aldosterone and vasopressin cause the kidneys to retain sodium (salt). Aldosterone also causes the kidneys to excrete potassium. The increased sodium causes water to be retained, thus increasing blood volume and blood pressure.
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12
Q

What is the net effect of aldosterone?

A

water retention and increased blood pressure

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13
Q

ADH ____ urine

A

concentrates

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14
Q

The net effect of ADH

A

water retention and increased blood pressure

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15
Q

What is the function of the respiratory system?

A
  • gas exchange
  • oxygen diffuses down its concentration gradient into the blood, and carbon dioxide diffuses down its concentration gradient out of the blood and back into the lungs.
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16
Q

path of air

A

Mouth/nose → pharynx → larynx → trachea → bronchi → bronchioles → alveoli

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17
Q

What is tidal volume?

A

the volume of air that enters and exits the lungs during an average, unforced respiration

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18
Q

What is an inspiratory reserve volume (IRV) and expiratory reserve volume (ERV)?

A

This is the volume of additional air that can be exhaled or inhaled after a normal, unforced expiration or inhalation

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19
Q

What is residual volume?

A

amount of air left in the lungs after a forced, maximal exhalation

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20
Q

What is vital capacity?

A

total volume of air the lungs can hold at maximum inflation, minus the residual volume

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21
Q

The diaphragm moves ___ when it is flexed and moves __ when it is relaxed

A

down, up

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22
Q

The diaphragm moves __ during inhalation and __ during exhalation

A

down, up

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23
Q

Describe hemoglobin

A

quaternary protein made of four protein chains, two alpha and two beta. Each protein has an Fe- containing “heme” group at its center. Each heme can hold one O2 molecule.

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24
Q

How many oxygen atoms are carried on one molecule of Hb at 100% saturation?

A

8 oxygen atoms

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25
Q

Describe the oxygen dissociation curve. Whats on the x-axis and y-axis?

A

x-axis = partial pressure of O2 (mmHg)
y-axis = % saturation of Hb
looks like a hill with plateau

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26
Q

What caused a shift to the right of an oxygen dissociation curve?

A

increased [H+]
increased [CO2]
increased temperature
BPG

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27
Q

What causes a left shift of the oxygen dissociation curve?

A

decreased [H+], [CO2], temperature, or BPG

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28
Q

net equation for how CO2 dissolves in blood

A

CO2 + H2O→HCO3- + H+

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29
Q

What is the function of the cardiovascular system?

A

Deliver oxygen and nutrients to the cells and tissues of the body; pick up CO2 and waste
products and deliver them to the lungs and kidneys

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30
Q

Explain systemic circulation

A

Blood flows from the left ventricle, through the arteries, arterioles, capillaries, venules, veins, vena cava and back to the right atrium.

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31
Q

Explain pulmonary circulation

A

Blood flows from the right ventricle through the pulmonary arteries to the lungs and back through the pulmonary veins to the left atrium

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32
Q

Arteries __ the heart, and veins __ the heart

A

leave, return

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33
Q

How are the SA node, AV node and purkinje fibers related?

A

The electrical signal originates at the SA node, then spreads across both atria to the AV node. There is a slight delay, then the signal travels from the AV node down the bundle of His and through the Purkinje fibers. At the end of the Purkinje fibers the signal travels cell to cell through gap junctions.

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34
Q

Sympathetic NS activity ___ heart rate and blood pressure

A

increases

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35
Q

Parasympathetic NS activity __ heart rate and blood pressure

A

decreases

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36
Q

What are arteries?

A

muscular, thick-walled vessels that push blood through via rhythmic contraction

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37
Q

What are veins?

A

thin-walled vessels with little to no musculature that reply on a valve system to move blood back toward the heart

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38
Q

Describe how the interplay of hydrostatic and osmotic pressure accounts for the flow of fluid into and out of the capillary beds

A

On the arterial side of the capillary bed the hydrostatic pressure is at its maximum. At this same point, the osmolarity of the blood is greater than that of the interstitial fluid, creating an osmotic pressure that would drive fluid into the capillary. These two influences oppose one another, but the hydrostatic pressure is greater than the osmotic pressure, yielding a net filtration pressure (13 mmHg, driving fluid out of the capillary and into the interstitial fluid). On the venous side of the capillary bed the differences in osmolarity are about the same, but the hydrostatic pressure has decreased significantly. This makes the net filtration pressure negative and fluid flows out of the interstitial fluid and into the capillary

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39
Q

What are the functions of blood?

A

transport nutrients, gases, waste products and hormones to and from cells; regulate the extracellular environment; help maintain homeostasis; repair injuries; protect the body from foreign bodies (i.e., antigens)

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40
Q

What are the main characteristics of erythrocytes?

A

sacks of hemoglobin, immature RBCs start out with a nucleus and organelles, mature RBCs have no organelles

41
Q

Do erythrocytes undergo mitosis?

A

no, lack cellular machinery

42
Q

What leukocytes involved in?

A

immune system

43
Q

What are the granulocytes and agranulocytes?

A

granulocytes - neutrophil, eosinophil, basophil (short life)

agranulocytes - monocytes (become macrophages), lymphocytes (long life)

44
Q

What are platelets?

A

Tiny membrane-bound drops of cytoplasm.
- help with clotting factors
Platelets are derived from megakaryocytes

45
Q

What is hematopoiesis?

A

All blood cells develop from stem cells (undifferentiated cells) in the bone marrow

46
Q

Type A blood has what kind of antigens? Type B? Type AB? Type O?

A

A- A antigens only
B- B antigens only
AB- both
O- no antigens

47
Q

To avoid mistakes on blood typing questions, always focus on the ___

A

recipient

48
Q

What is the function of the lymphatic system?

A

Gather excess interstitial fluid and return it to the blood

remove from the interstitial spaces proteins and other molecules too big to be taken up by the capillaries

monitor the blood and lymph for infection

49
Q

What are lymph nodes?

A

filled with lymphocytes

monitor blood for foreign antigens and fight infections

50
Q

How does lymph travel through lymph vessels?

A

Backward flow is restricted
eventually drains into two main vessels = right lymphatic duct and the thoracic duct, which both dump back into the blood stream by merging with large veins in the lower portion of the neck

51
Q

What does the nervous system include?

A

brain, spinal cord, peripheral nerves, neural support cells, and sensory organs

52
Q

neurons are frozen in ___ phase

A

G0 phase (unable to divide)

53
Q

What kind of energy source do neurons use?

A

only glucose

don’t require insulin for glucose uptake

Have very low glycogen & oxygen storage capability and thus require high perfusion (blood flow)

54
Q

What is an action potential?

A

a dramatic change in the resting electrical potential across the membrane of a nerve cell

55
Q

What is the value of resting potential of a neuron?

A

-70mV

56
Q

What is the sodium/potassium pump?

A

An ATP pump that actively transports 3 Na+ ions out of the cell and 2 K+ ions into the cell per cycle. The net effect is more positive charge outside the cell and a progressively more negative charge inside the cell.

57
Q

What are voltage gated sodium channels?

A

integral proteins that change shape in response to an action potential

58
Q

What is depolarization? What charge value is associated with it?

A

the opening of the voltage gated sodium channels that causes a sudden spike in membrane potential (-70 to 40 mV)

59
Q

What is threshold potential?

A

minimum stimulus that is exerted upon the membrane to initiate the full action potential. about 55 mV

60
Q

When do voltage gated potassium channels open?

A

just before maximum depolarization is reached, the Na+ channels begin to close and the K+ channels begin to open

61
Q

What is repolarization?

A

from 40 mV to -70 mV (open potassium channels)

62
Q

what is hyperpolarization

A

The potassium channels are somewhat slow to close as the membrane potential approaches -70 mV. Thus, the membrane potential actually dips to around -90 mV before gradually returning to the resting potential.

63
Q

What is the difference between the absolute refractory period and the relative refractory period?

A

absolute - portion of time during which an action potential cannot be initiated regardless of the strength of the stimulus

relative - portion of time during which the membrane is hyperpolarized (i.e., is more negative than at normal resting potential). During this time, a second action potential can be initiated, but a stronger-than-normal stimulus will be required.

64
Q

When do the sodium channels close?

A

at the peak of depolarization

65
Q

What are the 2 kinds of synapses?

A

Electrical - gap junctions between cells that electrical signals to pass quickly from cell-to-cell (found in retina, smooth muscle, cardiac muscle and CNS

chemical- small gap between axon terminal and other neuron

66
Q

What is the most common enzyme that breaks down neurotransmitter?

A

acetylcholinesterase

67
Q

agonist vs antagonist

A

agonist - activator

antagonist - inhibitor

68
Q

What are the three neuron types?

A

sensory (afferent)
motor (efferent)
interneurons - connect efferent and afferent (90% of neurons like this)

69
Q

What hormones are produced in the anterior pituitary gland?

A

FSH, LH, ACTH, hGH, TSH and Prolactin

70
Q

What hormones are produced in the posterior pituitary gland?

A

ADH and oxytocin

71
Q

What regulates the hormones released by the pituitary gland?

A

hypothalamus (eg Gonadotropin releasing hormone)

72
Q

What hormone is made in the parathyroid?

A

PTH (parathyroid hormone)

73
Q

What hormones are made in the pancreas

A

glucagon and insulin

74
Q

What hormone is released from the thyroid?

A

calcitonin

75
Q

What hormone is released from the embryo/placenta?

A

hCG (human chorionic gonadotropin)

76
Q

What are the 5 steroid hormones?

A

cortisol, aldosterone, estrogen, progesterone, testosterone

77
Q

What are the 4 tyrosine derivative hormones?

A

T3, T4, epinephrine, norepinephrine

78
Q

How are lipid-soluble and water-soluble hormones transported?

A

lipid soluble- require protein carrier or vesicle

water-soluble - dissolve in blood readily

79
Q

Hormones always act to return the system to ____ conditions

A

homeostatic

80
Q

What is the location, class, and function of ACTH?

A

made in anterior pituitary, water-soluble, stimulates the adrenal cortex to release stress hormones (glucocorticoids)

81
Q

What is the location, class, and function of LH?

A

anterior pituitary, peptide, causes ovulation, stimulates the secretion of sex hormones estrogen and testosterone

82
Q

What is the location, class, and function of FSH?

A

anterior pit, peptide, stimulates the growth of follicle and production of sperm

83
Q

What is the location, class, and function of TSH?

A

anterior pit, peptide, stimulates the release of T3/T4 from the thyroid

84
Q

What is the location, class, and function of hGH?

A

anterior pituitary, peptide, stimulates growth throughout body

85
Q

What is the location, class, and function of prolactin?

A

anterior pit, peptide, stimulates milk production in the breasts

86
Q

What is the location, class, and function of ADH?

A

posterior pit, peptide, causes the collecting duct to become permeable to h20, concentrating the urine

87
Q

What is the location, class, and function of oxytocin?

A

posterior pit, peptide, stimulates uterine contractions and milk secretion during nursing

88
Q

What is the location, class, and function of parathyroid hormone?

A

parathyroid, peptide, increases blood calcium by stimulating proliferation of osteoclasts, uptake of Ca2+ in the gut, and reabsorption of Ca in kidney

89
Q

What is the location, class, and function of Insulin?

A

pancreas, peptide, stimulates uptake and storage of glucose into blood

90
Q

What is the location, class, and function of glucagon?

A

pancreas, peptide, stimulates gluconeogenesis and release of glucose

91
Q

What is the location, class, and function of hCG?

A

egg/placenta, peptide, decreases blood calcium by inhibiting osteoclasts

92
Q

What is the location, class, and function of aldosterone?

A

adrenal cortex, steroid, increases Na+ resorption and K+ secretion at the distal conv. tubule and collecting duct, net increase in salts in plasma, increases bp

93
Q

What is the location, class, and function of cortisol?

A

adrenal cortex, steroid, increases gluconeogenesis in liver, stimulates fat breakdown

94
Q

What is the location, class, and function of testosterone?

A

testes, steroid, stimulates secondary sex characteristics and closing of epiphyseal plates

95
Q

What is the location, class, and function of estrogen?

A

ovaries, steroid, stimulates female sex organs, causes LH surge in menstruation

96
Q

What is the location, class, and function of progesterone?

A

ovaries, steroid, stimulates growth and maintenance of uterus during pregnancy

97
Q

What is the location, class, and function of T3 and T4?

A

thyroid, tyrosine-derivative (lipid soluble), increases basal metabolic rate

98
Q

What is the location, class, and function of epinephrine and norepinephrine?

A

adrenal medulla, tyrosine-derivative (water soluble), cause responses almost identical to a sympathetic ns (fight or flight)

mcat (15 decks)

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